It's hard enough to score a hit with your debut record, but once an artist clears that impressive hurdle, they're immediately faced with the question of how to follow it up. After delivering a multi-platinum smash with their first album, 1991's 'Cooleyhighharmony,' Boyz II Men dodged the sophomore jinx with a fairly novel approach: they never really went away.

'Cooleyhighharmony' didn't finish running its course until the summer of 1992, when the album's fourth single, 'Please Don't Go,' was serviced to pop and R&B radio -- and it was quickly followed in late June with 'End of the Road,' the foursome's contribution to the soundtrack to Eddie Murphy's 'Boomerang.' 'Road' was a record-setting smash, topping the Billboard charts from August through November and walking away with a pair of Grammys -- and that was followed by their cover of 'In the Still of the Night,' a Top Five hit as part of the soundtrack to the TV miniseries 'The Jacksons: An American Dream.'

The following year saw a pair of Boyz II Men releases: A 'Cooleyhighharmony' re-release featuring new tracks and 'End of the Road,' as well as the holiday collection 'Christmas Interpretations,' a Top 20 double-platinum hit in its own right. By the time they got around to delivering a proper follow-up to their debut, they weren't coming back so much as simply continuing a three-year run of chart domination.

And sure enough, when their second LP -- fittingly titled 'II' -- arrived in stores on Aug. 30, 1994, it was immediately one of the bigger hits of the year, debuting at No. 1 on Billboard's albums chart and selling more than 300,000 copies in its first week. Considering how enthusiastically fans and radio programmers had embraced their "hip hop doo-wop" sound, no one truly expected them to substantially alter the formula for 'II,' and they didn't -- in fact, they doubled down on it.

Although the group's benefactor, New Edition and Bell Biv Devoe member Ricky Bivins, had left their stable to focus on setting up his own label, his fellow 'Cooleyhighharmony' co-producer Dallas Austin returned -- and he was joined by a Who's Who of early '90s hitmakers, including Babyface, L.A. Reid, Jimmy Jam and Terry Lewis, and Tony Rich. All the biggest names in R&B wanted to work with Boyz II Men, and they all brought their best stuff to the table.

'II' wasn't strictly an all-star affair, however; five of the album's tracks were co-written and produced by the then-unknown duo, Tim Kelley and Bob Robinson -- a.k.a. Dallas Austin proteges' Tim & Bob. It's a testament to the strength of Boyz II Men's signature sound that the album's 14 tracks all sounded of a piece in spite of the small army of talent assembled behind the scenes; in fact, starting with the set's first single, 'I'll Make Love to You,' 'II' picked up right where the group had left off.

"Where they left off" was, of course, on top of the Hot 100, where 'I'll Make Love to You' spent a whopping 14 weeks -- and was only eventually unseated by the record's second single, 'On Bended Knee,' which hit the top spot twice during December of 1994 and January of 1995. Between those two hits and 'End of the Road,' Boyz II Men songs had spent 33 weeks at No. 1 on the pop charts since 1992.

That torrid run was bound to begin cooling off eventually, and the album's third single, 'Thank You,' was a comparative disappointment, peaking at No. 21 on the Hot 100 -- but they rebounded in the spring and summer with the Babyface number 'Water Runs Dry,' which went all the way to No. 2. All told, 'II' went down as the third best-selling album of 1995, and won the inaugural Best R&B Album Grammy at the 37th Grammy Awards in March of that year.

Late in '95, Boyz II Men didn't even need to rely on 'II' for hit singles: 'One Sweet Day,' their collaboration with Mariah Carey, was a Grammy-nominated No. 1 smash, and 'Hey Lover,' an LL Cool J single featuring backing vocals from the group, went to No. 3. Well into 1996, it was difficult to turn on the radio or MTV without hearing that familiar vocal blend -- even overseas, where their harmonies helped future Brazilian supermodel Gisele Bundchen learn to speak English.

Nothing lasts forever, however, and when the group returned the following summer with their third album, 'Evolution,' they found it difficult to build on the incredible success they'd achieved with their first two LPs. Although it brought back Babyface and Jam & Lewis and added the suddenly ubiquitous Puff Daddy to their stable of producers, spawning a pair of hit singles in '4 Seasons of Loneliness' and 'A Song for Mama' in the bargain, it didn't have anywhere near the staying power of its predecessors, and after the sales of 'Cooleyhighharmony' and 'II,' the double-platinum sales of 'Evolution' seemed somewhat disappointing.

By 2000, they'd departed Motown for Universal, where they released 'Nathan Michael Shawn Wanya,' which failed to even go platinum -- the same fate that awaited 'Full Circle' in 2003. By the following year, they were down to a trio, as bass vocalist Michael McCary departed the lineup due to health problems and personal conflicts, and subsequent efforts (including the covers sets 'Throwback, Vol. 1,' 'Motown: A Journey Through Hitsville USA,' and 'Love') have been more passionately received overseas, where Boyz II Men still enjoy a rabid fanbase.

They don't seem to be slowing down, though -- they booked a well-received Vegas residency in 2013, and although their highest-profile recent gig was singing about pretzel buns for the Wendy's fast food restaurant, they took the job to drum up publicity in advance of their most recent studio effort, 'Collide,' scheduled for a September 2014 release.

If their chart-topping days are permanently in the past, Boyz II Men co-founder Shawn Stockman professes not to miss the soaring heights of 'II' too much. "We don't really have any obligations to labels per se or image or trying to fit in or trying to be a part of whatever trend of culture," Stockman told CBS News. "It's the best feeling in the world to have that freedom."

And if their brand of "hip-hop doo-wop" has gone from sounding cutting edge to being seen as an anachronism, that's a label they wear with pride. "We came up at a time where there was an R&B group pretty much on every street corner, and every record company had one," Nathan Morris told NPR. "Now, it's dwindled down to solo artists, or the duets, or even bigger bands -- where you have bands like the Roots that got seven or eight people -- but the actual R&B group is a dinosaur."

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